Understanding Knobbed Cylinders

Four wooden blocks containing ten cylinders each. The dimensions of the cylinders increase progressively within each block. Each cylinder slides effortlessly yet precisely into its well, giving the child an enormous sense of satisfaction. The purpose of the cylinders is to develop visual perception of differences in dimension, to enhance understanding of dimensions, to encourage observation of the environment and to improve small muscle control, dexterity and hand-to-eye co-ordination in indirect preparation for writing. Holding the knobs between finger and thumb prepares the child for likewise holding the pencil. 


Block 1: (height and diameter of the cylinders decreases.) Each cylinder has the same diameter, they decrease in height successively from tall to short.  They differ in one dimension, height 



Block 2: (diameter decreases as the height increases.) Each cylinder has the same height, decreasing in diameter successively from thick to thin.  They differ in two dimensions, width and length.


Block 3: (diameter decreases as the height remains constant). Each cylinder has a diminishing diameter and an increasing height.  They differ inversely in three dimensions.



Block 4: (height decreases as the diameter remains constant). Each cylinder has both a diminishing diameter and height.  They differ regularly in three dimensions.


This set of four blocks, each with a series of cylinder insets which vary in size, help to develop the child’s visual discrimination of size as cylinder sets vary in height and or diameter. The knobbed cylinders indirectly prepare them for writing, through the physical handling of the cylinders by their knobs. 

Not only do students learn about size and dimension through the knobbed cylinders, but they gain vocabulary related to these topics, practice left to right progression and learn beginning problem solving skills. This knowledge enables them to observe and interact with their environment with greater awareness and insight.

The knobbed cylinders are self-correcting. When a piece does not fit, or is left over, the student will know he or she is not yet finished. Children are able to determine that a problem exists and take steps to address the problem without any intervention from a teacher. This produces a deep sense of accomplishment!

The knobbed cylinders are just one of many sensorial materials which support abstract concepts.